MnO2 Layer Research Articles

Mitigation of Jahn-Teller distortion and Na+/vacancy ordering in a distorted manganese oxide cathode material by Li substitution.

Layered manganese-based oxides are promising candidates as cathode materials for sodium-ion batteries (SIBs) due to their low cost and high specific capacity. However, the Jahn–Teller distortion from high-spin Mn3+ induces detrimental lattice strain and severe structural degradation during sodiation and desodiation. Herein, lithium is introduced to partially substitute manganese ions to form distorted P′2-Na0.67Li0.05Mn0.95O2, which leads to restrained anisotropic change of Mn–O bond lengths and reinforced bond strength in the [MnO6] octahedra by mitigation of Jahn–Teller distortion and contraction of MnO2 layers. This ensures the structural stability during charge and discharge of P′2-Na0.67Li0.05Mn0.95O2 and Na+/vacancy disordering for facile Na+ diffusion in the Na layers with a low activation energy barrier of ∼0.53 eV. It exhibits a high specific capacity of 192.2 mA h g−1, good cycling stability (90.3% capacity retention after 100 cycles) and superior rate capability (118.5 mA h g−1 at 1.0 A g−1), as well as smooth charge/discharge profiles. This strategy is effective to tune the crystal structure of layered oxide cathodes for SIBs with high performance.

Exchange bias in flexible freestanding La0.7Sr0.3MnO3/BiFeO3 membranes

Exchange bias lies in the core of cutting-edge technologies, for instance, high-density data storage, spin valves, and high-frequency magnetic devices. As the devices with flexibility have become vital in the forefront of technology, the maintenance of exchange bias under high flexion is highly desired. This paper reports the strong exchange bias in flexible freestanding La0.7Sr0.3MnO3/BiFeO3 membranes with decent mechanical durability. The La0.7Sr0.3MnO3 layer is biased strongly by the BiFeO3 layer even in the freestanding state. At the same time, the strain is demonstrated to affect the strength of the exchange bias of the La0.7Sr0.3MnO3/BiFeO3 bilayer. Furthermore, the saturation magnetization and exchange bias field of the freestanding La0.7Sr0.3MnO3/BiFeO3 membranes are preserved well after 1000 bending cycles. Our work on freestanding membranes paves the way for manufacturing advanced flexible spintronic devices.

Effect of Hot-Dip Galvanizing Process on Selective Oxidation and Galvanizability of Medium Manganese Steel for Automotive Application

A medium manganese steel with 7.5 wt.% Mn for automobile application was galvanized in a continuous Hot Dip Galvanizing (HDG) simulator under different galvanizing conditions. It was shown that the effects of dew point, annealing temperature and annealing atmosphere on the surface oxidation of steel could be comprehensively evaluated by the consideration of oxygen partial pressure P(O2). Although Mn2SiO4 was a thermodynamic stable phase when P(O2) varied from 10−28 to 10−21 atm, it was difficult to form Mn–Si–O composite oxide because there was no enrichment of silicon on the steel surface. So, this oxide was generally formed in the Fe substrate and had little effect on the galvanizability. With the increase in P(O2) above 10−25 atm, MnO particles in the form of the thermodynamic stable phase became coarser and tended to aggregate, which hindered the formation of a continuous inhibition layer, resulting in the defects of bare spots on the galvanized surface of the steel. When the oxygen partial pressure greater than 10−22 atm, film-like MnO layer was formed on the surface of steel sample, which obviously deteriorated the galvanizability. The galvanizability of the steel can be improved by the regulation of oxygen partial pressure; based on this, the reasonable zinc plating process parameters can be developed.

MnO2-based carbon nanofiber cable for supercapacitor applications

Supercapacitors (SCs) are an important option for energy storage. In this study, coaxial fiber cables with a 100-nm-thick manganese dioxide (MnO2) layer as the electrochemical active shell and 320-nm-diameter electrospun carbon nanofibers (CNFs) as the current-collecting core are fabricated. The MnO2 layer was electrodeposited onto the CNFs. The coaxial MnO2-CNFs cable mat was used for an SC study. A specific capacitance of 324.55 F/g was obtained at a current density of 0.5 A/g in 1 M Na2SO4 aqueous solution. The energy density and power density were 37.92 Wh/kg and 250 W/kg, respectively. The cable mat was assembled into a coin cell as a symmetric SC in 1 M Na2SO4 aqueous electrolyte. A specific capacitance of 47 F/g was achieved at 0.5 A/g with a potential window of 0 to 1.6 V. The binder-free and conductive-medium-free MnO2-CNFs cable mat is foldable and thus has potential for flexible SC devices.

Vertically Aligned ZnO/MnO2/Pedot Core-Shell Electrode in 3-D Nano-Architecture for High Energy-Power Density Pseudocapacitive Electrochemical Energy Storage

Electrochemical capacitors have emerged as the favored energy storage technology in diverse applications like hybrid electric vehicles, portable electronics, communication and smart grids. The key challenge is to increase the energy density alongside the high power density. The structured carbons based electrical double layer capacitors are common but fail to meet this requirement. The Faradaic charge storage mechanism based pseudo-capacitors offer enticing opportunities to bridge the energy and power density functionality gap between the battery and supercapacitors. One approach is to use conducting polymers (CPs), poly 3,4-ethylenedioxythiophene (pedot), polypyrrole and polyaniline etc wherein Faradaic processes are visualized as doping-dedoping of counter ions across vast interface with electrolyte. The other approach is to utilize reversible redox process exhibited by transition metal oxides (TMO) such as RuO2, MnO2 NiO, V2O5 etc which due to multivalent cation states and fast ions/electron kinetics can exhibit high charge storage capability. TMOs could have specific capacitance > 1000 Fg-1 but low electrical conductivity and low cycle stability are the main impediments. Conducting polymers have high electrical conductivity, but have poor mechanical strength and cyclic ability. Most past researches have tried to overcome these deficiencies in TMOs and ECPs by forming composite with carbon nanotubes, graphene etc. In this work we have investigated the metal oxide and conducting polymer composite electrode created in a specific nano-architecture that takes advantage of synergy of their potent properties coupled with the short ion diffusion paths and efficient electron exchange during redox processes.By hierarchical integration, supercapacitor electrodes in the 3-dimensional core-shell nanostructure have been designed based on ZnO nanorods at the core, redox active MnO2 layer and surface electro-polymerized pedot conducting polymer as shell. The vertically aligned ZnO nanorods array were hydrothermally grown over flexible graphite sheets to form the core template (Fig 1a). The ZnO nanorods were decorated with a thin ~120 nm layer of MnO2 nanoflakes by KMnO4+MnSO4 solution dip process to form an initial shell nanostructure. A microporous 250 nm thin layer of pedot was molecularly formed by insitu electro-pulsed polymerization over MnO2 surface to create a bi-layer shell (Fig 1b). The pedot shell with controlled porosity was achieved by short 10 ms high current (4 mA.cm-2) pulsed polymerization in aqueous solution of edot monomer, LiClO4 dopant and sodium dodecyl sulfate (SDS) surfactant. The ZnO / MnO2/ pedot core-shell nanostructure electrode shortens the ion diffusion path for fast ionic transport and renders large electroactive sites due to vast surface area. Pedot shell facilitates electronic transfer and ZnO core and imparts structural stability beside large surface area. The electrochemical energy storage performance of ZnO core, ZnO/MnO2 and ZnO/MnO2/Pedot core-shell electrodes was analyzed by cyclic voltammetry (CV), impedance spectroscopy (EIS), charge-discharge (CD) and long term cyclic tests in a three-electrode cell with Pt sheet as counter and Ag/AgCl as reference electrode in aqueous 1M sodium sulfate mediumThe Raman spectra analysis shows MnO2 shell forms in birnessite Mn(IV) state uniformly over ZnO nanorods. The pedot is highly conjugated (ClO4 ions) with sufficient micro-porosity for MnO2 to access electrolyte (LiClO4) and possible Li-ion incursion in pedot and MnO2. CV analysis establishes redox behavior of ZnO-MnO2 core-shell and with pedot shell further increase in areal capacitance >1090 F.g-1 with near rectangular CV plots (Fig 2a). The scan rate dependent study of surface charge and ion diffusion limitation shows that pedot layer mitigates poor electronic conduction in MnO2 shell and provided diffusive pathways for the ions thus enhancing capacitive properties (Fig 2b). This is further affirmed from the Nyquist plots showing nonexistent Warburg region indicating inconsequential diffusion limitation and the near vertical imaginary impedance indicating high pseudocapacitance. The 1.0- 3.0 mA cm-2 CD plots of ZnO/MnO2/pedot core-shell electrodes are triangular with minimal resistive drop and ~91% Coulomb efficiency. The ZnO/MnO2/core-shell shows energy density of 25.6 Wh kg-1 and power density 2.6 kW kg-1 and a significantly improved rate capability is realized with added pedot shell as evidenced by power density 20.8 kW.kg-1 corresponding to energy density of 37.9Wh.kg-1 .The cyclic stability tested over 6000 CD cycles show the usual capacitance fading for 900 cycles and highly stable performance thereafter and perhaps beyond 6000 cycles as the CD plots were in triangular without any change in resistive drops (Fig 2c). The supercapacitor device based on two symmetrical ZnO/MnO2/core-shell electrodes was similarly investigated. This paper will report on the significant research findings on the synergistic electrochemical action of nano MnO2 with molecularly integrated microporous pedot over ZnO nanorod array in a 3-dimensional nanoarchitecture Figure 1

Enhanced performance of dye-sensitized solar cell with thermally stable natural dye-assisted TiO2/MnO2 bilayer-assembled photoanode

This study reports the performance analysis of an organic dye-sensitized solar cell (DSSC), introducing MnO2 as an electron transport layer in TiO2/MnO2 bilayer assembly. The DSSCs have been fabricated using TiO2 and TiO2/MnO2 layer-by-layer architecture films onto fluorine-doped tin oxide (FTO) glass and sensitized with natural dye extracted from Malvaviscus penduliflorus flower in ethanol medium. The counter electrode was prepared to layer copper powder containing paste onto FTO's conductive side by the doctor's blade method. The optical, morphological, and structural properties of photoanodes were explored via ultraviolet–visible, field emission scanning electron microscopy, and X-ray diffraction analyses. Moreover, dye complexity and thermostability of dyes were characterized via Fourier-transform infrared spectroscopy and thermogravimetric analyses. The iodide/triiodide (i.e., I−/I3−) redox couple of electrolyte solution was employed as a charge transport medium between the electrodes. Finally, photoanode and counter electrode sandwiches were assembled to envisage the photovoltaic performance potential under simulated AM 1.5G solar illumination using 100 mW cm–2 light intensity. The as-fabricated DSSC comprising TiO2/MnO2 bilayer assembly exhibited 6.02 mA cm–2 short circuit current density (Jsc), 0.38 V open-circuit voltage (Voc), 40.38% fill factor, and 0.92% conversion efficiency, which is about 200% higher compared to the assembly devoid of MnO2 layer.

Adsorption mechanism of typical VOCs on pristine and Al-modified MnO2 monolayer

Layered MnO2 is widely concerned due to its excellent adsorption performance of volatile organic compounds (VOCs). In this work, the first-principles calculations were carried out to thoroughly investigate the adsorption mechanism of typical VOCs (formaldehyde, benzene and methyl chloride) on pristine and Al-modified MnO2 monolayer surfaces. The result shows that there are weak physical interactions between VOCs molecules and MnO2 monolayer, however, the modification by Al atom dramatically enhance these interactions, which can be classified as chemical adsorption. Specifically, the best adsorption performance occurs in the adsorption process of benzene molecule on the Al-modified MnO2 monolayer (with the adsorption energy of −2.416 eV). Besides, the difference of adsorption energy (−2.044 eV, nearly 10 times increase) between pristine MnO2 monolayer and Al-modified MnO2 monolayer demonstrates that the Al atom used for surface modification can dramatically enhance the adsorption performance of MnO2 layer for formaldehyde. Additionally, the projected density of state and charge density difference results confirm that Al atom plays a role of tie to connect these VOCs and MnO2 monolayer. Therefore, the Al-modified MnO2 monolayer is expected to be a promising VOCs adsorbent.

The Mechanical Effect of MnO2 Layers on Electrochemical Actuation Performance of Nanoporous Gold.

This study investigated the electrochemical actuation behavior of nanoporous material during the capacitive process. The length change of nanoporous gold (npg) was in situ investigated in a liquid environment using the dilatometry technique. The mechanical effect of MnO2 layers was introduced in this work to improve the actuation characteristics of the npg samples. Our work found that the actuation behavior of npg sample could be significantly modulated with a covering of MnO2 layers. The electrochemical actuation amplitude was efficiently improved and strongly dependent on the thickness of MnO2 layers covered. Aside from the amplitude, the phase relation between the length change and the electrode potential was inverted when covering the MnO2 layer on the npg samples. This means the expansion of the npg samples and the contraction of samples covered with the MnO2 layer when electrochemical potential sweeps positively. A simple finite element model was built up to understand the effect of the MnO2 layer. The agreement between the simulation result and the experimental data indicates that the sign-inverted actuation-potential response of nanoporous gold contributes to the mechanical effect of MnO2. It is believed that our work could offer a deep understanding on the effect of the MnO2 layer on the electrochemical actuation and then provide a useful strategy to modulate the actuation performance of nanoporous metal materials.

Electrochemical Behaviors of MnO2 on Lead Alloy Anode during Pulse Electrodeposition for Efficient Manganese Electrowinning

The electrochemical performances of deposited MnO2 on lead alloy anode by pulse current (PC) and direct current (DC) electrodeposition in manganese sulfate solution were investigated by performing measurements of galvanostatic polarization, cyclic voltammetry (CV), and Tafel tests. The composition and morphology of MnO2 were observed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The anode deposited with MnO2 layers by PC electrodeposition presented a lower anodic potential of 60 mV and more uniform potential oscillating attractor with fractal dimension of 1.0337 compared with those of DC electrodeposition. In addition, MnO2 layers exhibited excellent corrosion resistance because less intermediate oxide Mn(III) appeared in anode deposits. Furthermore, the cathodic current efficiency improved by 3.11∼3.77% and energy consumption decreased by 5.30∼8.17% after galvanostatic electrolysis for 2∼8 h by using PC instead of DC for manganese metal electrodeposition. As an external control method, PC electrodeposition not only regulated the structure and surface morphology of MnO2 but also affected the anode electrochemical behaviors and cathode manganese metal deposition. Electrochemical oscillations and other characteristics of anode reaction described in this study could inspire future work on promoting the whole electrowinning process.

Fabrication and characterization of MnO2-Coated carbon fabrics from silk for shape-editable supercapacitors

Supercapacitor (SC) fabrics have received considerable research interests due to their inherently flexible and wearable attributes. In the meantime, advanced wearable electronics devices with editability and programmability are much desired. Herein, a highly flexible and shape-editable carbonized silk fabric (CS) covered by a MnO2 layer was fabricated via a facile high-temperature carbonization process followed by a hydrothermal treatment. The flexible CS played an essential role in the editability of the shape-editable supercapacitor (SESC). Whereas the introduction of MnO2 greatly improved the hydrophilicity and capacitance performance of CS as it promoted electrolyte penetration and offered abundant electroactive sites. The SESC was assembled using two pieces CS-MnO2-10 as the electrodes. And it exhibited a high specific capacitance of 105.00 F g−1 at a current density of 0.25 A g−1 with a high energy density (14.58 W h kg−1 at a power density of 0.25 kW kg−1). Moreover, owing to the excellent flexibility and editability of CS-MnO2-10, the assembled SESCs could be easily edited to desired shapes. This work paved a road for the manufacturing of innovative energy storage devices to power various advanced electronic devices.

3D Bicontinuous Structure of a Pseudocapacitive Ultrathin Shell/Carbon Core: A Novel Electrode for Thin-Film Supercapacitors with High Areal Energy Density

Thin-film micro-supercapacitors (MSCs) with high areal capacitance are in great demand due to their wide application in ultra-compact energy storage devices. Carbon electrodes coated with high pseudocapacitance materials have typically been applied, but the increased resistance and pulverization by the pseudocapacitive materials still require improvement. To tackle this issue, we present a 3D bicontinuous structure of the pseudocapacitive shell and carbon core. Specifically, the 3D carbon structure is fabricated using multibeam interference lithography, and conformal thin layers of MnO2 or polyaniline (PANI) are obtained by electrodeposition. This electrode maintains a monolithic carbon conductive structure, even with a pseudocapacitance material coating. The conformal pseudocapacitive shell exhibits low resistance and structural integrity in redox reactions. MnO2– or PANI–carbon electrode MSCs achieve areal capacitance of 4.93 or 26.4 mF cm–2, respectively. The highest areal energy density of 3.67 μW h cm–2 is obtained for the PANI–carbon electrode MSC. This value is superior to the values achieved in recent thin-film MSCs, which demonstrates the advantages of 3D bicontinuous structures.

Multifunctional Smart Yolk-Shell Nanostructure with Mesoporous MnO2 Shell for Enhanced Cancer Therapy.

Manganese dioxide (MnO2) nanostructures have aroused great interest among analytical and biological medicine researchers as a unique type of tumor microenvironment (TME)-responsive nanomaterial. However, reliable approaches for synthesizing yolk-shell nanostructures (YSNs) with mesoporous MnO2 shell still remain exciting challenges. Herein, a YSN (size, ∼75 nm) containing a mesoporous MnO2 shell and Er3+-doped upconversion/downconversion nanoparticle (UCNP) core with a large cavity is demonstrated for the first time. This nanostructure not only integrates diverse functional components including MnO2, UCNPs, and YSNs into one system but also endows a size-controllable hollow cavity and thickness-tunable MnO2 layers, which can load various guest molecules like photosensitizers, methylene blue (MB), and the anticancer drugs doxorubicin (DOX). NIR-II fluorescence and photoacoustic (PA) imaging from UCNP and MB, respectively, can monitor the enrichment of the nanomaterials in the tumors for guiding chemo-photodynamic therapy (PDT) in vivo. In the TME, degradation of the mMnO2 shell by H2O2 and GSH not only generates Mn2+ for tumor-specific T1-MR imaging but also releases O2 and drugs for tumor-specific treatment. The result confirmed that imaging-guided enhanced chemo-PDT combination therapy that benefited from the unique structural features of YSNs could substantially improve the therapeutic effectiveness toward malignant tumors compared to monotherapy.

Pseudocapacitance of chemically stable MnO2-NiO mixture layer on highly conductive Sb doped SnO2 nanowire arrays

We report the electrochemical properties of MnO2–NiO mixture layer that is coated on highly conductive SnO2 nanowires. In this study, the effect of the nanowire conductivity and coating composition on the pseudocapacitic performance was systematically examined. To control the electric conductivity of the nanowire, Sb was doped into SnO2 during vapor–liquid-solid (VLS) process. Subsequently, pure or NiO added MnO2 layer was electrochemically deposited on SnO2 nanowire arrays. Structural studies show that the electrodeposition layer uniformly and conformally covered the nanowires. Low concentration Sb doping (up to 5 at%) increases the electric conductivity of the nanowires which work as an electron transport layer of the pseudocapacitor. Electrochemical studies indicate that the addition of NiO to MnO2 promotes a charging/discharging process through Faraday reaction by changing the oxidation mechanism of MnO2. These results guide a design of the metal oxide mixture for the pseudocapacitor application.

Effect of La0.67Sr0.33 MnO3 Insertion Layer on the Ferroelectric and Resistive Switching Behaviors of PbZr0.52Ti0.48O3/Nb:SrTiO3 Heterostructures

Recently, ferroelectric resistive switching (RS) effect in the ferroelectric/semiconductor heterostructures has been widely studied and the RS performance has been greatly improved. However, the relationships between ferroelectric and RS behaviors as well as interface structure of ferroelectric/semiconductor heterostructures need to be further studied. Herein, a [Formula: see text][Formula: see text]MnO3 (LSMO) layer with the thickness of 7 nm is inserted into [Formula: see text][Formula: see text]O3/Nb:SrTiO3 (PZT/NSTO) heterostructures, and its effects on the ferroelectric and RS behaviors are investigated. The PZT/NSTO heterostructures show significantly asymmetric ferroelectric loops, and the RS ratio in which can reach to three orders of magnitude. However, by inserting the LSMO layer, the ferroelectric loops became relatively symmetric, but the RS effect almost disappeared. It can be considered that the LSMO layer affects the interfacial energy band structure of the PZT/NSTO heterostructures, which makes ferroelectric polarization lose its effect on the modulation of the depletion layer width. Therefore, the existence of the adjustable depletion layer is very important for the RS effect of ferroelectric/semiconductor heterostructures.

Воздействие некоторых сложных хемостимуляторов и модификаторов на термооксидирование InP

Воздействие некоторых сложных хемостимуляторов и модификаторов на термооксидирование InP

Structural and optical properties of (Zn,Mn)O thin films prepared by atomic layer deposition

This paper investigates manganese-doped zinc oxide (ZnMnO) thin films grown using the atomic layer deposition (ALD) technique. ZnO and MnO layers were deposited alternatively using diethyl zinc and manganese (III) acetylacetonate (Mn(acac)3) as metallic precursors. A suppressed growth rate for both materials was observed during the growth of ZnMnO samples, which is due to reduced adsorption of the precursor molecules on the surface of the sample. Structural characterization of the ZnMnO films shows a weak polycrystalline structure for the as-deposited thin films. On the other hand, thermally annealed samples demonstrated a textured polycrystalline structure with a distinct (002) orientation. A red shift in the near band edge absorption was observed by increasing the Mn:Zn ratio. The results of this work demonstrate the potential in ALD growth of high-quality wide bandgap ZnMnO thin films that can be used as an active semiconductor material in memory and logic devices.

Aqueous-processable surface modified graphite with manganese oxide for lithium-ion battery anode

A facile strategy to control the interfacial energy at graphite-water interface is introduced by coating the hydrophobic graphite powder with a hydrophilic manganese oxide layer. This modification not only improves the aqueous dispersion stability of graphite particles, but also supplements the low lithium ion storage capacity of graphite due to the high lithium ion uptake capability of manganese oxide. A catalytic reaction between graphite particles and permanganate ions leads to the formation of MnO2 layer on the surface of graphite particles. Successively, annealing the resulting composite powder in a reducing atmosphere transforms surface MnO2 to MnO. The electrode prepared with MnO-coated graphite powder showed the specific capacitance of 402 mAh g−1 at a current density of 25 mA g−1, which is higher than that of the pristine graphite electrode (338 mAh g−1 at 25 mA g−1). In addition, the electrode exhibited outstanding charge–discharge cycling stability for 100 cycles at a current density of 100 mA g−1 without any fluctuation or abnormal increase in the capacity that is often observed in transition metal oxide-based electrodes. It also showed excellent rate capability comparable to the pristine graphite electrode.

High specific energy ternary nanocmposite polyaniline:Manganeese dioxide@ MWCNT electrode for asymmetric supercapacitor

• A co-axial system of polyaniline and MnO 2 was generated over functionalized MWCNT. • An asymmetric supercapacitor device is fabricated which can be cycled in wide voltage window of 2 V. • Due to synergism, electrochemical performance is enhanced. A layer of highly dispersed manganese oxide (MnO 2 ) nanoparticles in polyaniline (PANI) was deposited over functionalized MWCNT using insitu chemical polymerization. Obtained Coaxial MWCNT/PANI:MnO 2 ternary nanocomposite was used as positive electrode with MWCNT negative electrode in an asymmetric supercapacitor (ASC) device. The proposed design utilizes the pseudo capacitive charge in a different potential range of the ASC device. Microstructural investigations confirmed the wrapping of MWCNT by a layer of MnO 2 dispersed PANI. This leads to highly porous and homogeneous morphology of the ternary nanocomposite. Due to synergism between PANI and MnO 2 nanoparticles over MWCNT, the electrical properties of the ternary nanocomposite are significantly improved. It is observed that the proposed ASC device can be cycled up to a cell voltage 2.0 V reversibly. The above combination of materials in ASC device exhibited very high specific energy 190 Wh/kg and specific power at 1 mA/cm 2 . This device demonstrated better rate capability by maintaining 78% specific capacitance after continuously 2000 charge discharge cycles.

Strain-induced local structural change and its effect on the superconducting properties of GdBa2Cu3O7-x /La0.7Sr0.3MnO3 heterostructure

The effect of ferromagnetic buffer layer on the superconducting properties of relatively thick, high temperature superconductors is investigated. Elaborately designed heterostructure films consisting of epitaxial GdBa2Cu3O7-x (GdBCO) on top of two types of La0.7Sr0.3MnO3 (LSMO) layer and particles, were fabricated by pulsed laser deposition. Unlike a typical superconducting/ferromagnetic system where the superconducting properties are degraded, the superconducting properties of our GdBCO/LSMO system are enhanced depending on the local structural details of the GdBCO and LSMO layers. The strain state of GdBCO characterized from the bond length of the Cu-O and the Mn-O bonds lengths is observed to vary depending on the formation of LSMO. The phase diagram of Tc for the GdBCO/LSMO system established by the micro-strain of the Cu-O bond-length shows that Tc reaches its maximum at the critical micro-strain. This result suggests the importance of strain state in improving the superconducting properties of thick-GdBCO/LSMO films.

Inhibiting tumor oxygen metabolism and simultaneously generating oxygen by intelligent upconversion nanotherapeutics for enhanced photodynamic therapy

Hypoxia is one of the hallmarks of solid tumor, which heavily restricts the clinical cancer therapy treatments, especially for the oxygen (O2) -dependent photodynamic therapy (PDT). Herein, an intelligent multi-layer nanostructure was developed for decreasing the O2-consumption and elevating the O2-supply simultaneously. The cell respiration inhibitor –atovaquone (ATO) molecules were reserved in the middle mesoporous silicon layer, and thus were intelligently released at the tumor site after the degradation of gatekeeper of MnO2 layer, which effectively inhibit tumor respiration metabolism to elevate oxygen content. Meanwhile, the degradation of MnO2 layer can generate O2, further boosting oxygen content. Moreover, the inner upconversion nanostructures as the near infrared (NIR) light-transducers enable to activate photosensitizers for deep-tissue PDT. Systematic experiments demonstrate that this suppressing O2-consumption and O2-generation strategy improved oxygen supply to boost the singlet oxygen generation to eradicate cancer cells under NIR light excitation. Better still, superior trimodality imaging capabilities (computed tomography (CT), NIR-II window fluorescence, and tumor microenvironment-responsive T1-weighted magnetic resonance (MR) imaging) of the nanoplatform were evaluated. Our findings offer a promising aproach to conquer the serious hypoxia problem in cancer therapy by turning down the O2 metabolism aveneue and simultaneously generating O2.